1. Field of the Invention
This invention relates to a method for manufacturing an electronic device, and more particularly to a method for manufacturing an electronic device in which electronic components are mounted on a transparent substrate via an anisotropic conductive film.
2. Background Art
Conventionally, a liquid crystal display (LCD) is manufactured by laminating two glass substrates together via a liquid crystal layer and mounting a chip including a circuit for driving the LCD on a non-display region of one of the glass substrates. The chip is mounted by pressure bonding bumps of the chip to electrodes formed on a surface of the glass substrate via an anisotropic conductive film (ACF). The anisotropic conductive film is made of a thermosetting resin film with many conductive particles dispersed therein. When the anisotropic conductive film is pressurized in the film thickness direction, the conductive particles are brought into contact with each other to exhibit conductivity in the film thickness direction, but insulation is maintained in the film plane direction by the intervention of the resin between the conductive particles. The electrodes formed on the glass substrate and the bumps of the chip, which are arranged at a fine pitch, can be connected to each other without short circuit to adjacent electrodes or bumps by connecting them via the anisotropic conductive film.
Here, whether the chip is mounted on the glass substrate in a favorable manner can be tested by observing the electrodes from the backside of the glass substrate. More specifically, when the bumps of the chip are pressured to the electrodes of the glass substrate via an anisotropic conductive film, the conductive particles in the anisotropic conductive film are pressed to the electrode, and thereby fine convexities are formed as indentations on the backside of the electrode, that is, its surface in contact with the glass substrate. These indentations are detected by observing the backside of the electrode using a differential interference microscope. The number of indentations is counted for each electrode. Electrodes with the number of indentations less than a reference value can be determined as defective in connection (see, e.g., JP-A 2005-227217(Kokai)).
However, in the conventional method described above, although an electrode actually having defective connection can be discovered, it is impossible to predict the occurrence of defective connection in advance. If defective connection of an electrode actually occurs, the LCD having this electrode is forced to be sent to a repair process, incurring additional cost.